The invention relates to a sensor controlled leveling device comprising a laser sensor for detecting a datum plane in relation to a reference plane established by a laser beam and electronic processing means, via which at least one servo drive connected with the sensor is shifted to oppose a change in the relative attitude of the laser sensor in relation to the reference plane in order to produce a correction of deviation of the sensor towards the reference plane.
In accordance with another aspect the invention relates to a leveling device comprising an attitude detector with a container, a liquid located in said container and a float therein, and two cooperating pairs of contacts for detecting a change in attitude of the float and for actuating a servo drive whose input is connected with the pairs of contacts for automatic correction of deviation, the two pairs of contacts being so placed oppositely at the end parts of the float that in each case one contact member of each contact pair is on the float and the respective other contact member is supported on the housing.
In many engineering applications precise apparatus for leveling is becoming of increasing importance. Such equipment is intended not only for measuring and detecting certain horizontal or angular settings but also for producing a correction of deviations, for example to keep a machine in alignment.
A detector device for detecting the oblique setting of a machine frame is described for example in the German examined specification 3,200,545.
This detector device comprises a container which is secured to the frame of a machine and is filled with a liquid in which there is a float which is so designed that the upthrust of the float is less when the liquid is at an angle owing to an oblique setting of the machine frame and the float is subject to less frequent or less severe changes in comparison with the weight of the float so that less frequent or reduced alterations are involved. There is furthermore a device for indicating or detecting the obliquity of the float which consists of two contact sensors which are arranged at the ends of the longitudinally extending float and cooperate with further contacts.
The U.S. Pat. No. 3,660,840 describes a level indicating device which also has a float above which four contacts are arranged in the form of a cross and are mounted on a plate forming part of the device. The float bears against a central screw on the cover of the device so that a bearing or support point is formed about which the float pivots. The device is however only used to indicate, for example, the angle of camping vehicle. While the initially mentioned prior art device with the leveling means is often completely unsuitable for many applications, since evaporation or the like will cause a change in the level of the liquid so that accurate leveling will be impossible and thus such a device may only be used for very coarse work in which the attitude or orientation of something is detected with a large degree of approximation with automatic adjustment in the opposite direction to a deviation, as for example on a constructional machine, the second prior art device suffers from the disadvantage that its attitude detecting device is only able to be used for indicating and not for automatic correction of deviations, for example on constructional machines. Furthermore the detector device may only be used for the adjustment of a horizontal attitude and not for use in connection with predetermined and presettable angular settings.
In practice there is frequently not only the problem of working the soil along a horizontal path or along a plane descending or ascending at a given angle, but also of leveling the ground at a certain selectable height.
In the prior art a reference plane for the height of leveling of the soil may be defined by a taut cord or a wire held between two points. However, more especially in the case of heavy earth moving machines there are likely to be serious inaccuracies.
Accordingly lasers have already been proposed for the alignment of constructional machinery. The laser is used to define a reference plane. A laser sensor is then mounted on an earth moving machine for instance. The laser sensor may then so operate a hydraulic system that the center of the receiver or sensor continually follows the laser beam. If the laser sensor drifts together with the earth moving machine upwards this will be detected by the laser sensor and the earth moving machine with the laser receiver mounted thereon will be moved downwards to correct the deviation and the laser receiver is returned to the reference plane as defined by the laser beam source unit so as to be exactly in the centered state. Laser sensors so far proposed are however not only very high in price but more especially have the disadvantage that they only make it possible to attain a continuous alignment of the laser sensor in relation to the reference plane as defined by the laser beam with substantial error fluctuations.